Attachment of hepatitis C virus to cultured cells: a novel predictive factor for successful interferon therapy.

In order to identify reliable predictive factors for the response to interferon (IFN) therapy, we examined 52 patients with chronic hepatitis C virus (HCV) infection who underwent IFN therapy. Titers of free virions that were not complexed with antibodies were determined by immunoprecipitation of the pretreatment sera with antihuman immunoglobulin. Cell attachment titers were determined by inoculating HPB-Ma cells, a human T-cell line, with the patients' pretreatment sera. A sustained remission was achieved in 9 out of 28 patients with genotype 1b infection and in 18 out of 24 patients with genotype 2 infection. The free virion titers and the cell attachment titers correlated well with the serum HCV RNA levels in patients with genotype 1b infection (r = 0.817, P < 0.001; r = 0.802, P < 0.001, respectively), but not in those with genotype 2 infection. They exhibited a high correlation with the responsiveness to IFN in all patients combined (P < 0.001). A multiple logistic regression analysis was performed to identify the factor most significantly associated with the response to IFN among all confounding factors. The analysis indicated that the cell attachment is the most reliable predictive factor regarding a favorable response to IFN therapy in patients with chronic HCV infection.